Since the early 1970's there has been a constant effort to improve the energy efficiency of cooling units which function on the air conditioning and refrigeration principle. As is well known, air conditioning and refrigeration systems function by relying upon the energy absorbed or released as a compressible fluid undergoes either pressure increase in a compressor or pressure decrease across a valve or other orifice. Typically, these systems rely upon phase changes from the gas to liquid state as a result of changes in pressure to effectuate energy transport. Such air conditioning and refrigeration units are utilized for large commercial installations either for refrigeration or freezing of perishable articles and the like as well as for climate control of large commercial buildings as well as individual dwellings. The energy efficiency of these units has been greatly increased through redesigned compressors, motors and other mechanical and design improvements. Improved methods for lubricating compressors have been developed so as to reduce the frictional energy which must be overcome in the compressor while new compressor designs have also been developed in an attempt to increase the energy efficiency of the systems.
However, a need still exists for continued energy improvement in the field of air conditioning and refrigeration systems.